Reuzo de vitro reduktas la konsumon de krudmaterialoj.

Because reuzo is a noun, meaning reuse as a concept or activity.

In Esperanto:

• uzi = to use
• reuzi = to reuse
• uzo = use
• reuzo = reuse

So Reuzo de vitro means reuse of glass. This whole noun phrase is the subject of the sentence.

Here de means of.

So:

• reuzo de vitro = reuse of glass

This is a very common Esperanto pattern: noun + de + noun.

For example:

• la pordo de la domo = the door of the house
• la koloro de la muro = the color of the wall

In this sentence, de vitro tells us what is being reused.

Because vitro is being used in a general, material sense: glass as a substance, not a specific piece of glass.

Esperanto often leaves out la when speaking about something in a general sense.

So:

• vitro = glass, as a material
• la vitro = the glass, a specific glass object or specific glass already known from context

Here the idea is general: reusing glass as a material reduces raw-material consumption.

The ending -as marks the present tense in Esperanto.

So:

• reduktas = reduces / is reducing

In a sentence like this, the present tense is often used for a general truth or fact, just like in English:

• Exercise improves health.
• Reuzo de vitro reduktas la konsumon de krudmaterialoj.

It does not necessarily mean only right now; it can also express a general principle.

The -n ending marks the direct object in Esperanto.

Here, the thing being reduced is la konsumon.

So the structure is:

• Reuzo de vitro = subject
• reduktas = verb
• la konsumon de krudmaterialoj = object

Without the -n, the grammar would be wrong.

This is one of the most important features of Esperanto: the direct object usually gets -n.

Because Esperanto often uses la when talking about a specific or identifiable thing, even when English might be more flexible.

Here la konsumon de krudmaterialoj refers to the consumption of raw materials in a general but conceptually definite sense. It is the particular kind of consumption relevant to the statement.

In practice, Esperanto often uses la with abstract nouns more readily than English does.

You may also sometimes see similar sentences without la, depending on style, but la konsumon is very natural here.

Again, de means of.

So:

• la konsumon de krudmaterialoj = the consumption of raw materials

This tells us what is being consumed.

Notice the difference between the two de phrases in the sentence:

• reuzo de vitro = reuse of glass
• konsumon de krudmaterialoj = consumption of raw materials

Same grammar pattern, different nouns.

Esperanto very often forms compound words by joining roots together.

Here:

• krud- = raw
• material- = material
• -o = noun ending
• -j = plural

So krudmaterialoj literally means raw materials.

This kind of compounding is extremely common in Esperanto and often more natural than using a separate adjective + noun structure.

A learner might expect something like krudaj materialoj, and that would be understandable, but krudmaterialoj is a normal, compact Esperanto compound.

Because raw materials are usually thought of as multiple materials rather than one single material.

The ending -j marks the plural:

• krudmaterialo = a raw material
• krudmaterialoj = raw materials

So the sentence is talking about reducing the consumption of raw materials in general.

You can tell from both word order and endings.

In this sentence:

• Reuzo de vitro is the subject
• reduktas is the verb
• la konsumon de krudmaterialoj is the object

The clearest clue is the -n on konsumon, which marks it as the direct object.

So even if Esperanto word order can sometimes be flexible, the -n ending helps you identify the role of the noun phrase very quickly.

Yes. For example, you might also see:

• La reuzo de vitro reduktas la konsumon de krudmaterialoj.
• Reuzado de vitro reduktas la konsumon de krudmaterialoj.

These are similar, but there are small differences:

• reuzo focuses on reuse as a result or concept
• reuzado emphasizes the process/activity of reusing
• adding la before reuzo can make the subject feel a bit more definite

The original sentence is already natural and correct. These alternatives are just stylistic variations.